That number of killings is double the amount from last Christmas weekend when six people were killed, according to The Chicago Tribune. And last year's tally ran from Thursday evening to Sunday evening, covering one more day than this year.

The bloody Christmas weekend comes toward the end of a record year of violence in the nation's third-largest city. More than 750 people have been killed in Chicago in 2016, marking the first time in nearly two decades that the number slain has exceeded 700, according to the Tribune.

Johnson said this weekend's violence was mostly in areas with a history of gang conflicts -- on the city's south and west sides.

The deadly Christmas weekend began just before 11 p.m. on Friday when two men, ages 20 and 21, were fatally shot, police said.

Shortly after midnight on Saturday, a 27-year-old was fatally shot in the abdomen and head, police said.

Early Christmas Day, a 21-year-old was found in a home's backyard with a fatal gunshot wound to the head, police said.

The final killings of the weekend were late Christmas Day when two young men, ages 18 and 21, were shot during an incident on a porch that left five others injured, police said.

The Chicago Tribune says the two were brothers and were on the porch with their relatives when a gunman ran out from an alley and began firing. After hearing the news, the brothers’ mother screamed and collapsed; three people carried her down the sidewalk, The Chicago Tribune reported.

The shooter fled the scene, police said, and no arrests have been made.

Johnson said at a news conference this afternoon that the majority of this weekend's shootings were "targeted attacks" by gangs against "potential rival gang members" at holiday gatherings.

Ninety percent of those fatally wounded this weekend had gang affiliations, criminal histories and were pre-identified by the police department's "strategic subject algorithm" as being a potential offender or victim of gun violence, Johnson added.

Johnson is urging state lawmakers to help change the "reckless gun culture."

Johnson said he hopes a new law will give judges autonomy to sentence repeat gun offenders to the middle- or high-end of the range, because he says repeat offenders are not willing to "play by society's rules."

He said he hopes the legislation will give cops "a fighting chance" to hold offenders accountable to begin to change the narrative in the city.